Connection Between BMI and Intelligence

BMI or Body Mass Index has become an extremely popular tool in recent years for determining health and health risk for all people but specifically children. I remember being screened once every year in middle school and high school to determine if I was underweight, overweight, or just right. This was one of the biggest days of the year, partially because we missed class for it, but that is neither here nor there. BMI is an important statistic because of its health implications, but what other implications could it have? Could someone’s BMI predict their Intelligence Quotient (IQ)? A A Tabriz and a team of scientists from The University of North Carolina, John’s Hopkins University, and The Shahid Beheshti University of Medical Sciences in Tehran, Iran wanted to find out.


The team, led by Tabriz, selected students from 74 different schools in 13 different provinces of Iran. They chose a diverse population to account for social and economic differences in different regions of the country. All together 1,151 preschool children were selected. Each child had to be accompanied by a parent and both child and parent were surveyed for data. Each pair was given a questionnaire that included questions about age, gender, history of education, location of home, age and education of parent, type of child birth, type of infant feeding and household income.  After the questionnaire was completed, students had their height and weight measured. Height was measured to the nearest tenth of a centimeter and weight was measured to the nearest tenth of a kilogram. With these measurements, the team was able to calculate each child’s BMI. Next, the team used the Wechsler Intelligence Scale for Children, 4th Edition to evaluate the intelligence of the children. Children were classified based on results. A score of over 130 as classified as very superior, between 120-129 was superior, 110-119 was normal brilliant, 90-109 was normal, 80-89 was normal awkward, 70-79 was borderline and below 70 was classified as mental retardation.


Tabriz and his team found a strong association between intelligence score and income, location of home, delivery type, type of infant feeding and parent’s education. Children that were delivered by caesarean section, children that were breast fed and those who lived in metropolitan areas were found to have higher scores. The only findings in regards to BMI were that students with abnormal BMI (either over or underweight) were more likely to have lower intelligence scores. However, there were too many other variables that had strong associations to say if BMI is a strong indicator.



Tabriz A., Sohrabi M., Parsay S., Abadi A., Kiapour N., Aliyari M., Ahmadi F., Roodaki A. Relation of intelligence quotient and body mass index in preschool children: A community-based cross-sectional study. Nutr. Diabetes. 2015;5:e176. doi: 10.1038/nutd.2015.27. [PMC free article] [PubMed] [Cross Ref]

One thought on “Connection Between BMI and Intelligence

  1. Emma G Schadler

    Hey Christopher, I like how this article seems completely random, but in the end there appears to be reason behind the connection. Although I don’t think BMI and IQ are directly related, if there is any relationship it is likely to be due to the third variables that tie the two factors together, such as the other variables the scientists in the study measured. Low BMI likely correlates to a low income household, which typically correlates to a decrease in good learning opportunities. High BMI is a little more interesting, since if we must link low and high together, it would mean explaining that high BMI correlates to a high income household. And high income households usually have higher learning options available to them. Perhaps high BMIs might then be linked to depression or unhealthy eating, which can both be linked to living in a distressed household.

    Either way, while I don’t think BMI and IQ are directly correlated, it seems that there is some intrigue behind researcher other connections that link them. Here are some other factors that can affect the development of intelligence throughout people’s lives.

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